ByJames KaufmannDecember 24, 1984

English Creek, by Ivan Doig. New York: Antheneum. 339 pp. $15.95. There are two main characters in Ivan Doig's ''English Creek.'' One is 14 -year-old Jick McCaskill: He narrates the novel, and much of the story concerns his coming of age. The other character looms over, under, and around this book; it is the land, the Two Medicine country in western Montana.

Doig has always given land and landscape loving attention. In ''This House of Sky'' (1978), ''Winter Brothers'' (1980), and ''The Sea Runners'' (1982) he demonstrated his devotion to place, and in this novel, the first of a projected trilogy about the McCaskill family, he does so again.

Somewhere just past the middle of ''English Creek,'' Jick is telling us of his ride each morning to put up hay with his uncle, Pete Reese. It is just before dawn when he starts:

The ford north of the ranger station Pony and I would cross; if there was enough moon the wild roses along the creek could be seen, pale crowds of them; and in a few minutes of climbing we came atop the bench of land which divides the two creek drainages. Up there, at that brink of dawn hour, the world revealed all its edges. Dark lines of the tops of buttes and benches to the north, toward the Two Medicine River and the Blackfeet Reservation.

The Sweetgrass Hills bumping up far on the eastern horizon like five dunes of black sand. The timbered crest of Breed Butte standing up against the stone mountain wall of the west. What trick of light it is I can't really say, but everything looked as if drawn in heavy strokes, with the final shade of night penciled in wherever there was a gulch or coulee.

Jick is only coming into what we might call an awareness of adult life. His older brother, Alec, has had a fight with his parents and, instead of going to college, is planning to be a cowboy. There are still plenty of them around Montana at this time - 1939. Alec takes off to ride for the Double W Ranch and to think about marrying the lovely Leona Zane, while Jick spends the summer haying, helping his father, Varick, occasionally visiting friends in the nearest town, and generally becoming conscious of curiosities of human nature.

Jick knows the simple pleasures of hard work, daydreaming, and special days like the Fourth of July, a holiday Doig renders as an extraordinary scene that includes a stunning speech by Jick's mother, Beth, on the history of the land they inhabit.

The end of this novel mustn't be disclosed if a reader is to enjoy the book to the fullest, but one can say it is dramatic, and it unfurls a large lesson for Jick, who comes to know himself through a better understanding of his mother and father.

''English Creek'' is old-fashioned in the best sense of the word: Doig is concerned with telling a story that entertains, and he is also concerned with the novel's moral and ethical implications. He mounts no soapbox, however. Doig is a regional writer. He is committed to the Pacific Northwest, and he draws it as lovingly as Thomas Hardy drew Wessex and as accurately as Raymond Chandler limned Los Angeles. He deserves to be better known. If you haven't read him, Consider ''English Creek'' the place to start, then work backward.